Beginning in 1963 under the guidance of John Craighead, researchers began examining Golden Eagle Ecology in South-Central Montana. At that time, their focus was on nesting ecology, prey selection, and the effects of pesticides on the birds. For the time, this was powerful, important information to collect. Later, it became the foundation for what is now the longest running dataset on Golden Eagle nesting trends in all of North America.
Migrating Golden Eagle Numbers Decline
In the mid 1990s, Derek Craighead returned to resurvey the study site his father had helped to research 30 years prior. Upon his return, Derek documented eagles in many of the previously located historic territories, and he also found similar nest density and productivity rates. At the time, the Golden Eagle population in the Rocky Mountain region was thought to be recovered and stable; it was of little concern to biologists. However, this period marked the beginning of what became an annual decline in migrating Golden Eagle count numbers at established locations along known migration routes. This trend soon caught the attention of biologists and land managers, and they shifted their focus to Goldens as concern grew for their population numbers.
While migration counts are invaluable to monitoring population trends, they are unable to reveal the cause of changing trends. With that in mind, CBS biologists saw an opportunity to continue the research started almost 50 years ago on Golden Eagle nesting demographics in South-Central Montana, to collect information that could potentially help mitigate the decline of Golden Eagles in the Rocky Mountain west.
Beginning in 2010, personnel from Craighead Beringia South embarked on the third phase of the Golden Eagle nesting project. The entire study site was revisited in the spring, during the early nesting period, and locations of current territories and active nest sites were documented. During this initial visit, we were able to document the use of nest sites that dated all the way back to the original survey period -- this means that Golden Eagles had been nesting in the same area for at least 50 years! After their initial visit, the crew went back on two additional occasions in order to assess productivity. The number of young entering the population (i.e. productivity) is potentially the most critical factor affecting the population decline and is a missing piece of the puzzle that managers need to make informed decisions. Our goals are to develop seasonal distribution models based on aerial surveys for eagles, and to describe important overwintering areas for sub-adult eagles. The project also seeks to understand the dispersal and movements of juvenile eagles in contrast to sub-adults that originate farther north from Canada and Alaska. Data collection will continue for at least one more year through aerial surveys and satellite tracking.
Bureau of Land Management (BLM)
United States Fish and Wildlife Service (USFWS)
The Bureau of Land Management